LRTK Phone Accuracy: Smartphone AR Point Cloud Scanning Can Be This Accurate!

Table of Contents

• What is LRTK Phone accuracy? Centimeter-class positioning achievable with smartphones (cm level accuracy (half-inch accuracy))

• Accuracy and challenges of conventional smartphone AR point cloud scanning

• How LRTK Phone improves accuracy

• Comparison with professional surveying instruments: the capabilities of LRTK Phone accuracy

• New possibilities for smartphone point cloud scanning enabled by higher accuracy

• What simple surveying enabled by LRTK looks like

• Conclusion

• FAQ

What is LRTK Phone accuracy? Centimeter-class positioning achievable with smartphones (cm level accuracy (half-inch accuracy))

LRTK Phone is a groundbreaking system that enables centimeter-class high-precision positioning using only a smartphone (particularly the iPhone). Normally, smartphone GPS positioning accuracy is said to be on the order of several meters, but with LRTK Phone you can determine position with surveying-instrument-level accuracy of just a few centimeters. This is achieved by combining a dedicated ultra-compact GNSS receiver that utilizes the positioning technique RTK (Real-Time Kinematic), a smartphone app, and cloud services. By simply attaching a small device that fits in your pocket to your smartphone, you can obtain position information with accuracy comparable to expensive surveying equipment.

This cm-precision positioning (cm level accuracy (half-inch accuracy)) allows accurate coordinates to be attached to any data acquired by the smartphone. For example, if you scan the surroundings with an iPhone’s built-in LiDAR sensor or AR functions, you can assign latitude, longitude, and elevation in a global coordinate system to the acquired point cloud. Before the advent of LRTK Phone, point clouds scanned with smartphones only had relative coordinates, and additional adjustments were required to align them with actual field coordinates. By using the high-precision position information from LRTK Phone, smartphone AR point cloud scans can be given absolute (global) coordinates, enabling the capture of 3D data with scale and spatial relationships that match the real site exactly.

Accuracy and challenges of conventional smartphone AR point cloud scanning

3D scanning using AR technology on smartphones has attracted attention as an easy way to acquire on-site 3D data. However, conventional smartphone AR point cloud scanning had several accuracy-related challenges. Specifically, the following issues were problematic.

• GPS accuracy limits: The built-in GPS on typical smartphones commonly has errors on the order of several meters, which is insufficient for surveying large sites or precise positioning. Even when plotting on a map, deviations of several meters can occur, making accurate position records difficult to use.

• Accumulation of AR scan errors: Smartphone AR scans (e.g., iPhone LiDAR scans) acquire point clouds while estimating the device’s position using the device’s IMU sensors and camera. As travel distance increases, errors can gradually accumulate, causing distortions or scale shifts in the scanned 3D model. In some cases, lengthwise or heightwise errors of several percent can occur, which is a problem in situations requiring high precision.

• Lack of absolute coordinates: Scan data from a smartphone alone is basically recorded in a local coordinate system (relative coordinates valid only for that session). When overlaying later with other surveying data or design drawings, manual transformations and alignment to control points are required, which is time-consuming. Especially for surveying applications, the inability to acquire data in an absolute coordinate system such as national geodetic coordinates has been a major constraint.

As described above, the ease of use came at the cost of accuracy limits in smartphone AR point cloud scanning, so the conventional wisdom was that “it’s useful for simple records and visualization, but difficult to use for precise surveying.”

How LRTK Phone improves accuracy

LRTK Phone technology addresses these challenges and dramatically improves the accuracy of smartphone AR point cloud scanning. Here’s how LRTK Phone achieves high precision.

1\. Centimeter positioning with RTK-GNSS: LRTK Phone is equipped with a high-performance GNSS receiver that receives signals not only from GPS but from multiple satellite positioning systems (GNSS). Using the RTK method, it receives real-time correction information from a base station to greatly reduce positioning errors. As a result, in open-sky environments LRTK Phone typically reaches a “Fix” positioning state in about 20–40 seconds, and can determine the smartphone’s position with astonishing accuracy of approximately horizontal ±2 cm (±0.8 in) and vertical ±4 cm (±1.6 in). While conventional smartphone GPS accuracy was on the order of ±10 m (±32.8 ft), using RTK improves accuracy by orders of magnitude.

2\. Integration with the smartphone’s AR functions: The high-precision position information from LRTK Phone is integrated into the smartphone’s AR engine (e.g., iPhone ARKit). This allows the smartphone to maintain an accurate estimate of its position in the real world as it moves through space. Whereas normal AR scans suffer from some error in self-localization, adding LRTK’s correction data makes device tracking more accurate and substantially reduces point cloud distortions and scale drift. In other words, each point acquired by the smartphone’s camera or LiDAR is mapped to the correct geographic coordinates in real time.

3\. Acquisition of point clouds with absolute coordinates: Through the combination of high-precision positioning and AR integration, point clouds scanned with a smartphone are recorded from the start with absolute coordinates (e.g., global geodetic coordinates). This means you can immediately use the 3D data as surveying deliverables without special calibration. For example, when scanning terrain or structures, the point cloud can be overlaid with maps or CAD design data right away, dramatically improving post-processing efficiency. Additionally, the acquired point cloud can be checked in real time on the smartphone, allowing you to add scans in missing areas if necessary and confirm data quality on site.

4\. Dedicated app and cloud service: The LRTK Phone system includes a dedicated iPhone app and a cloud service (LRTK Cloud) for data management and processing. The app provides an intuitive UI to handle everything from starting positioning to point cloud scanning and AR display in a single workflow. On the cloud, uploaded point clouds can be viewed on a 3D map, distances/areas/volumes can be measured, and comparisons with design models can be performed. This software support allows high-precision field data to be put to use immediately.

Through this hardware-software integration, LRTK Phone dramatically enhances both the accuracy and practicality of smartphone AR point cloud scanning.

Comparison with professional surveying instruments: the capabilities of LRTK Phone accuracy

Even if the principle promises high accuracy, you might wonder, “Can a smartphone really measure that accurately?” Let’s look at results comparing LRTK Phone accuracy with professional surveying instruments.

Internal and field verifications confirmed that coordinates obtained with LRTK Phone are comparable to those measured by class-1 GNSS receivers (surveying GPS) used by surveyors. Specifically, the same point was measured with both LRTK Phone and a class-1 GNSS receiver, and the coordinates were compared. The coordinate differences in both horizontal and vertical directions were on the order of a few millimeters (at most under 5 mm (0.20 in)), falling within the margin of error and showing almost identical values. This means that despite being a small device attached to a smartphone, LRTK Phone achieves sub-centimeter accuracy comparable to professional surveying equipment.

In another test, known-point coordinates were measured dozens of times with LRTK Phone and the mean and variance were analyzed to evaluate stability. The variation between measurements was very small, the mean was extremely close to the theoretical value, and consistently high reproducibility was observed. This shows that LRTK Phone does not merely produce a single lucky high-accuracy measurement, but maintains high accuracy repeatedly.

The important point is that this level of accuracy can be obtained easily on site. Traditionally, achieving centimeter-level positioning required large GNSS equipment on tripods or total stations operated by specialized surveyors. LRTK Phone can extract equivalent accuracy with a smartphone-sized, handheld device, lowering the barrier for field surveying work. High accuracy yet easy to use — this is the greatest strength of LRTK Phone accuracy.

New possibilities for smartphone point cloud scanning enabled by higher accuracy

With LRTK Phone dramatically improving the accuracy of smartphone AR point cloud scanning, a variety of previously difficult applications have become practicable. Here are some possibilities enabled by higher accuracy.

First, applications in civil engineering and construction sites. Tasks formerly performed with surveying instruments, such as as-built surveys and terrain measurements before and after earthwork, can be completed by walking around the site with a smartphone fitted with LRTK Phone and performing point cloud scans. For example, when calculating volumes for large embankments or excavations, accurate volume calculations can be derived from smartphone-scanned point clouds. Because the point clouds include absolute coordinates, they can be immediately compared with design cross-sections or reference elevations to determine how much material needs to be added or removed. LRTK Phone is ideal for routine as-built management. Tasks that previously required specialized contractors can be performed frequently by in-house staff, greatly improving the speed and accuracy of progress management and quality control.

Next, possibilities for infrastructure inspections and disaster sites. High-precision 3D point clouds can be easily obtained, enabling applications such as displacement measurement of bridges and tunnels or assessing slope collapse conditions. For example, in the immediate aftermath of a disaster, using an LRTK Phone–equipped smartphone allows quick capture of detailed 3D data without survey teams needing to spend long periods in hazardous areas. The data can be shared instantly via the cloud, enabling remote experts to collaborate in real time and quickly plan countermeasures. Being able to complete initial surveying and recording with a single smartphone is a major advantage.

Furthermore, combining with AR technology creates new use cases. In earlier low-accuracy AR, overlaying virtual design models on site suffered from significant misalignment and was impractical. With LRTK Phone, BIM/CIM models and other digital data can be displayed precisely aligned with the real world. This lets you verify design intent on site at full scale and in the correct position. Applications such as AR visualization of design proposals or AR display of buried utilities to guide excavation work become feasible. Accuracy-assured AR can reduce construction errors, improve on-site sharing of design intent, and serve as a key tool for construction DX (digital transformation).

The high-precision smartphone AR point cloud scanning enabled by LRTK Phone is not merely a technical improvement but has the potential to transform on-site workflows. Affordable, easy-to-use tools that allow anyone to handle high-quality 3D data make tasks once reserved for specialists accessible to the field team, speeding decision-making and reducing costs.

What simple surveying enabled by LRTK looks like

LRTK Phone is not only for point cloud scanning with smartphones but is also a trump card for making all kinds of on-site measurements simple — a solution for “simple surveying.” Traditionally, surveying required specialized equipment and high-level skills, but with LRTK, field staff can complete small measurements on their own where and when needed.

Here are the main capabilities of simple surveying with LRTK.

• One-touch point surveying: With LRTK Phone attached to a smartphone, you can record the coordinates of a specific point with a single tap. If the positioning state is Fix, the obtained coordinates have errors within a few centimeters in latitude, longitude, and elevation. For example, boundary points or arbitrary feature locations can be measured accurately by one person approaching and recording the point.

• Distance and area measurement without a tape: The dedicated app allows you to immediately measure distances between two points or areas enclosed by polygons using the on-site point cloud or photos. There is no need to pull a tape measure or use a surveying calculator. Just tap the required points on the smartphone screen and high-precision lengths and areas are calculated automatically.

• Immediate volume and earthwork calculations: Volumes of embankments and excavations can be computed on site from point cloud data. For example, if you want to know the amount of soil produced by earthworks, scan around the area with your smartphone, upload to the cloud, and accurate earthwork quantities are calculated in a short time. This enables immediate decisions on truck arrangements and disposal planning.

• Stakeout and position-guidance navigation: The LRTK app includes a “coordinate guidance (stakeout)” function that guides the user to a specified coordinate. As you approach a preset target point, the remaining distance is displayed on the screen in centimeter units and notifies you when you reach the precise location. This allows stakeout tasks that previously required two-person teams (guided by a total station for angle and distance) to be done solo with a smartphone. Using AR display, you can also show a 3D model of a flag or marker at the target location for visual guidance.

• Geotagged photo records: Field photos taken with the smartphone can be tagged with high-precision position and orientation information. When reviewing photos later, you can see exactly where and in which direction each was taken, which is useful for reporting and long-term comparison. The cloud also supports plotting photos on a map so shooting locations are obvious at a glance.

As described above, the LRTK Phone–centered system makes surveying and measurement tasks that previously required specialists or costly equipment surprisingly accessible. The idea of “measure immediately when it occurs to you on site” becomes a reality, speeding decisions and enhancing on-site autonomy. LRTK presents a modern approach to simple surveying that fits the needs of today’s fieldwork.

Conclusion

We have examined in detail the accuracy of LRTK Phone, which is revolutionizing smartphone AR point cloud scanning, from its mechanisms to use cases. The ability to achieve centimeter-class positioning on a smartphone and immediately assign absolute coordinates to point cloud data is invaluable. LRTK Phone transforms the smartphone from a mere gadget into a full-fledged surveying tool, accelerating the digitization and efficiency of fieldwork.

The combination of high accuracy and ease of use offered by LRTK Phone creates new opportunities across not only surveying and construction management but all uses of spatial data. From precise point cloud scanning to simple surveying and AR visualization, tasks that were once performed separately can now be seamlessly connected with a single smartphone. If you want to collect accurate on-site data more easily or promote DX in your operations, smartphone surveying with LRTK is well worth considering. Experience the cutting-edge LRTK Phone accuracy for yourself.

FAQ

Q: What does LRTK Phone stand for?

A: "LRTK" is the name of our solution, referring to a high-precision positioning system that leverages RTK (Real-Time Kinematic) technology. "Phone" indicates that it integrates with smartphones, hence the combined name LRTK Phone. The difference from typical GPS is that real-time correction information dramatically improves positioning accuracy.

Q: What level of positioning accuracy can LRTK Phone achieve?

A: Under favorable conditions (open sky with sufficient satellite reception) and when an RTK fixed solution (Fix) is obtained, you can expect about ±2 cm (±0.8 in) accuracy horizontally and about ±4 cm (±1.6 in) vertically. In actual tests, differences compared to professional surveying GPS have been within a few millimeters, so the accuracy is at a level where errors are barely perceptible.

Q: How large an area can be scanned with a smartphone at one time?

A: The range of a smartphone AR scan depends on the environment, but as a guideline you can continuously capture point clouds over tens to hundreds of meters. By using LRTK Phone, positional accuracy is maintained even when moving long distances; for example, you can walk along a slope about 200 m (656.2 ft) long and scan it in 1–2 minutes. For very wide areas, you can divide the area and scan multiple sections and then merge the data later.

Q: Do I need specialized knowledge or qualifications to use it?

A: No. Basic operations are completed within the smartphone app and the system is designed to be intuitive for users without specialized knowledge. Simply attach the LRTK Phone to your smartphone and press the app’s start-positioning button — high-precision positioning begins automatically, and you can follow the app prompts to scan and measure. With a short training or by reading the manual, field staff can perform measurements with surveyor-like accuracy.

Q: Can it be used indoors or where GPS signals are unavailable?

A: In indoor locations or places like tunnels where GNSS signals cannot be received, real-time high-precision RTK positioning does not function. In such cases, relative measurements using the smartphone’s AR functions alone are possible, but absolute coordinate accuracy cannot be guaranteed. However, by using previously obtained reference points to work in a local coordinate system or other workarounds, useful results can still be achieved. The technology is most powerful in open outdoor environments, but with appropriate adjustments it can be useful in various scenarios.

Q: Which smartphones are supported?

A: Currently the solution targets iPhone. iPhones equipped with LiDAR scanners (models from iPhone 12 Pro onward) can fully utilize the AR point cloud scanning features. Expansion to other models is under consideration, but the latest iPhones are compatible with LRTK Phone functionality. The app is available on the App Store, so with a supported iPhone you can try high-precision positioning right away.